Mitochondria definition: Mitochondria are sac like cell organelles involved in energy production through breakdown of carbohydrate in presence of oxygen. In short they are termed as power houses of the cell.
In simple terms, mitochondria are termed as energy currencies of the cell or power generators of the cell etc. There are studied to a great extent due to this role of body energy production even in some complex disease and disorders.
Characteristics of mitochondria:
Mitochondria are organs of special importance. These organelles are absolute requirements to sustain life of the cell and its physiological activities. The characteristics of mitochondria are interesting both in anatomical and physiological terms.
They are double membrane sac like structures. The outer membrane is oval shaped without folding. While the inner membrane is folded to form partitions termed cristae. In the gap of these folding lies the matrix which encompasses all the enzymes and other substances which can help in production of energy as ATP.
For more on mitochondria anatomy refer the page.
They are present in almost all the cells of the body except in Red Blood Cells.
Mitochondria are self replicable i.e. they can multiply on their own without the requirement of cell to divide. This characteristic feature helps replacement of old, worn out and damaged mitochondria with new and healthy mitochondria. This process happens many times in life cycle of a cell.
Mitochondria have their own genetic material as single stranded DNA instead of a double stranded one as in the cell nucleus.
They have capacity to generate mRNA which helps in formation of proteinacious enzymes required for respiratory chain.
The mitochondria are transported or migrated through the long nerve cell. The Brain is high energy demanding organ and hence the number of mitochondria are more in a nerve cells. Nerve cells have a central nerve body and an extended lengthy axon with a nerve tip at the end. The mitochondria are formed in nerve body and then migrate towards the nerve tip. Nerve tip is involved in signal transmission, nerve growth and branching (plasticity). Hence healthy mitochondria are concentrated at the tip of nerve endings to cope up with the high energy demand and those mitochondria which are worn out, aged and damaged are migrated back from nerve tip to nerve body for digestion.